1. Field of the Invention
The present invention relates to a presentation device used in combination with an overhead projector for projecting an image on a screen, and more particularly, to a presentation device which is placed on a stage of an overhead projector, to be substituted for data copies, such as manuscripts, graphs, etc.
2. Description of the Related Art
Overhead projectors are conventionally used to project enlarged images of data copies on a screen in places where many people gather to attend conferences, lectures, seminars, etc. Each projector is provided with a transparent stage for carrying a data copy, a light source housed in the body of the projector, and a magnifying reflector disposed over the stage, outside the body of the projector. The light source serves to radiate light through the stage. The reflector is used to reflect the light transmitted through the stage or the data copy, toward the screen.
In the overhead projector described above, the data copy on the stage must be formed of a transparent film bearing information to be projected, in view of the principle of projection on the screen. In projecting the image by means of the overhead projector, therefore, it takes a lot of time to prepare data copies in advance. If the number of copies to be used for the projection is large, moreover, the replacement of the data copy on the stage requires much time and labor.
In consideration of these circumstances, it has recently been proposed that a panel unit with a liquid crystal panel of a transmission type be used in place of a data copy formed of a transparent film. The panel unit, i.e., the liquid crystal panel, is connected to a so-called personal computer, especially a portable personal computer, to be usable as a presentation device of the computer. Thus, the panel of the panel unit can receive image signals from the personal computer, and display images based on the signals.
When in service, the panel unit is placed on the stage of the overhead projector. The liquid crystal panel of the panel unit, however, is liable to be adversely influenced by heat from the light source in the projector. It may be proposed, therefore, to attach legs to the underside of the panel unit, in order that a gap of a predetermined distance is defined between the panel unit and the stage of the projector, during the use of the panel unit. If the panel unit is provided with legs, however, its size or thickness must be substantial, and besides, a case for the protection of the panel unit or the liquid crystal panel is inevitably bulky. Accordingly, the whole presentation device, composed of the panel unit and the case, would be too large in size to be portable.